[dpdk-dev] [PATCH 1/2] net/mlx5: fix Rx packet padding

[dpdk-dev] [PATCH 1/2] net/mlx5: fix Rx packet padding

[Yongseok Koh]

Rx packet padding is supposed to be set by an environment variable -
MLX5_PMD_ENABLE_PADDING, but it has been missing for some time by mistake.
Rather than using such a variable, a PMD parameter (rxq_pkt_pad_en) is
added instead.

Fixes: a1366b1a2be3 ("net/mlx5: add reference counter on DPDK Rx queues")
Cc: stable@dpdk.org

Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
Reviewed-by: Erez Ferber <erezf@mellanox.com>
---
 doc/guides/nics/mlx5.rst | 27 +++++++++++++--------------
 drivers/net/mlx5/mlx5.c  | 18 +++++++++++++++---
 2 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index 5ddca44eed..3f168b1613 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -233,20 +233,6 @@ Environment variables
   enabled and most useful when ``CONFIG_RTE_EAL_PMD_PATH`` is also set,
   since ``LD_LIBRARY_PATH`` has no effect in this case.
 
-- ``MLX5_PMD_ENABLE_PADDING``
-
-  Enables HW packet padding in PCI bus transactions.
-
-  When packet size is cache aligned and CRC stripping is enabled, 4 fewer
-  bytes are written to the PCI bus. Enabling padding makes such packets
-  aligned again.
-
-  In cases where PCI bandwidth is the bottleneck, padding can improve
-  performance by 10%.
-
-  This is disabled by default since this can also decrease performance for
-  unaligned packet sizes.
-
 - ``MLX5_SHUT_UP_BF``
 
   Configures HW Tx doorbell register as IO-mapped.
@@ -301,6 +287,19 @@ Run-time configuration
 
   - CPU having 128B cacheline with ConnectX-5 and Bluefield.
 
+- ``rxq_pkt_pad_en`` parameter [int]
+
+  A nonzero value enables padding Rx packet to the size of cacheline on PCI
+  transaction. This feature would waste PCI bandwidth but could improve
+  performance by avoiding partial cacheline write which may cause costly
+  read-modify-copy in memory transaction on some architectures. Disabled by
+  default.
+
+  Supported on:
+
+  - x86_64 with ConnectX-4, ConnectX-4 LX, ConnectX-5, ConnectX-6 and Bluefield.
+  - POWER8 and ARMv8 with ConnectX-4 LX, ConnectX-5, ConnectX-6 and Bluefield.
+
 - ``mprq_en`` parameter [int]
 
   A nonzero value enables configuring Multi-Packet Rx queues. Rx queue is
diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index a84e1afa09..741bc7fc07 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -54,6 +54,9 @@
 /* Device parameter to enable RX completion entry padding to 128B. */
 #define MLX5_RXQ_CQE_PAD_EN "rxq_cqe_pad_en"
 
+/* Device parameter to enable padding Rx packet to cacheline size. */
+#define MLX5_RXQ_PKT_PAD_EN "rxq_pkt_pad_en"
+
 /* Device parameter to enable Multi-Packet Rx queue. */
 #define MLX5_RX_MPRQ_EN "mprq_en"
 
@@ -486,6 +489,8 @@ mlx5_args_check(const char *key, const char *val, void *opaque)
 		config->cqe_comp = !!tmp;
 	} else if (strcmp(MLX5_RXQ_CQE_PAD_EN, key) == 0) {
 		config->cqe_pad = !!tmp;
+	} else if (strcmp(MLX5_RXQ_PKT_PAD_EN, key) == 0) {
+		config->hw_padding = !!tmp;
 	} else if (strcmp(MLX5_RX_MPRQ_EN, key) == 0) {
 		config->mprq.enabled = !!tmp;
 	} else if (strcmp(MLX5_RX_MPRQ_LOG_STRIDE_NUM, key) == 0) {
@@ -541,6 +546,7 @@ mlx5_args(struct mlx5_dev_config *config, struct rte_devargs *devargs)
 	const char **params = (const char *[]){
 		MLX5_RXQ_CQE_COMP_EN,
 		MLX5_RXQ_CQE_PAD_EN,
+		MLX5_RXQ_PKT_PAD_EN,
 		MLX5_RX_MPRQ_EN,
 		MLX5_RX_MPRQ_LOG_STRIDE_NUM,
 		MLX5_RX_MPRQ_MAX_MEMCPY_LEN,
@@ -735,6 +741,7 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
 	struct rte_eth_dev *eth_dev = NULL;
 	struct priv *priv = NULL;
 	int err = 0;
+	unsigned int hw_padding = 0;
 	unsigned int mps;
 	unsigned int cqe_comp;
 	unsigned int cqe_pad = 0;
@@ -1060,10 +1067,14 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
 	DRV_LOG(DEBUG, "FCS stripping configuration is %ssupported",
 		(config.hw_fcs_strip ? "" : "not "));
 #ifdef HAVE_IBV_WQ_FLAG_RX_END_PADDING
-	config.hw_padding = !!attr.rx_pad_end_addr_align;
+	hw_padding = !!attr.rx_pad_end_addr_align;
 #endif
-	DRV_LOG(DEBUG, "hardware Rx end alignment padding is %ssupported",
-		(config.hw_padding ? "" : "not "));
+	if (config.hw_padding && !hw_padding) {
+		DRV_LOG(DEBUG, "Rx end alignment padding isn't supported");
+		config.hw_padding = 0;
+	} else if (config.hw_padding) {
+		DRV_LOG(DEBUG, "Rx end alignment padding is enabled");
+	}
 	config.tso = (attr.tso_caps.max_tso > 0 &&
 		      (attr.tso_caps.supported_qpts &
 		       (1 << IBV_QPT_RAW_PACKET)));
@@ -1440,6 +1451,7 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 		qsort(list, n, sizeof(*list), mlx5_dev_spawn_data_cmp);
 	/* Default configuration. */
 	dev_config = (struct mlx5_dev_config){
+		.hw_padding = 0,
 		.mps = MLX5_ARG_UNSET,
 		.tx_vec_en = 1,
 		.rx_vec_en = 1,
-- 
2.11.0

[dpdk-dev] [PATCH 2/2] net/mlx5: fix deprecated library API for Rx packet padding

[Yongseok Koh]

In rdma-core library IBV_WQ_FLAG_RX_END_PADDING is renamed to
IBV_WQ_FLAGS_PCI_WRITE_END_PADDING. Way to query the capability is also
changed.

Cc: stable@dpdk.org

Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
Reviewed-by: Erez Ferber <erezf@mellanox.com>
---
 drivers/net/mlx5/Makefile    | 5 +++++
 drivers/net/mlx5/meson.build | 2 ++
 drivers/net/mlx5/mlx5.c      | 5 ++++-
 drivers/net/mlx5/mlx5_rxq.c  | 7 +++++--
 4 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/net/mlx5/Makefile b/drivers/net/mlx5/Makefile
index 688678ac84..9a7da18196 100644
--- a/drivers/net/mlx5/Makefile
+++ b/drivers/net/mlx5/Makefile
@@ -121,6 +121,11 @@ mlx5_autoconf.h.new: $(RTE_SDK)/buildtools/auto-config-h.sh
 		enum IBV_FLOW_SPEC_MPLS \
 		$(AUTOCONF_OUTPUT)
 	$Q sh -- '$<' '$@' \
+		HAVE_IBV_WQ_FLAGS_PCI_WRITE_END_PADDING \
+		infiniband/verbs.h \
+		enum IBV_WQ_FLAGS_PCI_WRITE_END_PADDING \
+		$(AUTOCONF_OUTPUT)
+	$Q sh -- '$<' '$@' \
 		HAVE_IBV_WQ_FLAG_RX_END_PADDING \
 		infiniband/verbs.h \
 		enum IBV_WQ_FLAG_RX_END_PADDING \
diff --git a/drivers/net/mlx5/meson.build b/drivers/net/mlx5/meson.build
index 6413cefd06..4540c455b7 100644
--- a/drivers/net/mlx5/meson.build
+++ b/drivers/net/mlx5/meson.build
@@ -103,6 +103,8 @@ if build
 		'mlx5dv_create_flow_action_packet_reformat' ],
 		[ 'HAVE_IBV_DEVICE_MPLS_SUPPORT', 'infiniband/verbs.h',
 		'IBV_FLOW_SPEC_MPLS' ],
+		[ 'HAVE_IBV_WQ_FLAGS_PCI_WRITE_END_PADDING', 'infiniband/verbs.h',
+		'IBV_WQ_FLAGS_PCI_WRITE_END_PADDING' ],
 		[ 'HAVE_IBV_WQ_FLAG_RX_END_PADDING', 'infiniband/verbs.h',
 		'IBV_WQ_FLAG_RX_END_PADDING' ],
 		[ 'HAVE_IBV_DEVX_OBJ', 'infiniband/mlx5dv.h',
diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 741bc7fc07..a913a5955f 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -1066,8 +1066,11 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
 				 IBV_RAW_PACKET_CAP_SCATTER_FCS);
 	DRV_LOG(DEBUG, "FCS stripping configuration is %ssupported",
 		(config.hw_fcs_strip ? "" : "not "));
-#ifdef HAVE_IBV_WQ_FLAG_RX_END_PADDING
+#if defined(HAVE_IBV_WQ_FLAG_RX_END_PADDING)
 	hw_padding = !!attr.rx_pad_end_addr_align;
+#elif defined(HAVE_IBV_WQ_FLAGS_PCI_WRITE_END_PADDING)
+	hw_padding = !!(attr.device_cap_flags_ex &
+			IBV_DEVICE_PCI_WRITE_END_PADDING);
 #endif
 	if (config.hw_padding && !hw_padding) {
 		DRV_LOG(DEBUG, "Rx end alignment padding isn't supported");
diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index 34c8338723..10b6ce0c12 100644
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -881,12 +881,15 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 		attr.wq.ibv.create_flags |= IBV_WQ_FLAGS_SCATTER_FCS;
 		attr.wq.ibv.comp_mask |= IBV_WQ_INIT_ATTR_FLAGS;
 	}
-#ifdef HAVE_IBV_WQ_FLAG_RX_END_PADDING
 	if (config->hw_padding) {
+#if defined(HAVE_IBV_WQ_FLAG_RX_END_PADDING)
 		attr.wq.ibv.create_flags |= IBV_WQ_FLAG_RX_END_PADDING;
 		attr.wq.ibv.comp_mask |= IBV_WQ_INIT_ATTR_FLAGS;
-	}
+#elif defined(HAVE_IBV_WQ_FLAGS_PCI_WRITE_END_PADDING)
+		attr.wq.ibv.create_flags |= IBV_WQ_FLAGS_PCI_WRITE_END_PADDING;
+		attr.wq.ibv.comp_mask |= IBV_WQ_INIT_ATTR_FLAGS;
 #endif
+	}
 #ifdef HAVE_IBV_DEVICE_STRIDING_RQ_SUPPORT
 	attr.wq.mlx5 = (struct mlx5dv_wq_init_attr){
 		.comp_mask = 0,
-- 
2.11.0

Re: [dpdk-dev] [PATCH 1/2] net/mlx5: fix Rx packet padding

[Shahaf Shuler]

Tuesday, January 15, 2019 7:39 PM, Yongseok Koh:
> Subject: [dpdk-dev] [PATCH 1/2] net/mlx5: fix Rx packet padding
> 
> Rx packet padding is supposed to be set by an environment variable -
> MLX5_PMD_ENABLE_PADDING, but it has been missing for some time by
> mistake.
> Rather than using such a variable, a PMD parameter (rxq_pkt_pad_en) is
> added instead.
> 
> Fixes: a1366b1a2be3 ("net/mlx5: add reference counter on DPDK Rx
> queues")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> Reviewed-by: Erez Ferber <erezf@mellanox.com>

Series applied to next-net-mlx, thanks.